1. Field of the Invention
This invention relates to a vacuum chamber, more particularly to an adjustable gate valve assembly for a vacuum chamber, which includes an angle-adjustable lid plate and which can achieve effectively an air-tight seal between the lid and a wall that defines an opening of the vacuum chamber.
2. Description of the Related Art
In some current high-technology industries, a large number of products have to be processed in a vacuum chamber of a vacuum processing device, which is sealed by means of a gate valve assembly. The gate valve assembly includes a lid plate, which presses against a wall defining the vacuum chamber and which covers an opening in the wall, through which the products can move. An annular sealing strip is clamped between the lid plate and the wall, and is disposed around the opening, thereby establishing an air-tight seal therebetween. Although the gate valve assembly can, seal the vacuum chamber, it suffers from certain drawbacks, as set forth below:
1. Difficulty in manufacturing and mounting of the lid plate:
To achieve a vacuum-tight seal between the lid plate and the wall, it is absolutely necessary to mount the same in parallel. As a result, there is a need for a relatively high precision during manufacture and assembly of the gate valve assembly and the wall.
2. Unable to maintain sealing of the vacuum chamber after long-term use:
Heating and cooling are performed frequently within the vacuum chamber, thereby resulting in deformation of the lid plate, which in turn affects adversely the sealing of the vacuum chamber.
3. Increase in manufacturing costs due to repeated processes:
In a case where the manufacturing process of a product has several machining steps to be performed respectively in different vacuum chambers, for example, in a process for forming a thin film on a liquid crystal display glass panel, which includes the steps of cleaning, first heating, first sputtering of metal, second heating, and second sputtering of metal, it is necessary for each of the machining steps to evacuate air from the chamber to form a vacuum before machining and to pressurize and unload after machining, thereby resultingin a time-consuming process.
An object of this invention is to provide a vacuum processing device, which is easy to manufacture and mount.
Another object of this invention is to provide a durable vacuum processing device, in which a vacuum chamber can be maintained effectively for a long amount of time.
Still another object of this invention is to provide a vacuum processing device, in which a product can be machined efficiently, thereby reducing the manufacturing costs of the product.
According to this invention, a vacuum processing device has at least one vacuum processing unit, which includes a housing defining a vacuum chamber, and a gate valve assembly. The valve assembly includes a rotating shaft, a lid plate for covering an opening in the housing so as to seal the vacuum chamber, and a connecting member connected fixedly to the rotating shaft. Each of several aligned adjustment rods connects the lid plate to the connecting member. The adjustment rods are disposed perpendicular to the lid plate. A plurality of resilient units are coupled to the adjustment rods, respectively, for biasing the lid plate away from the connecting member to press against a wall of the housing, which defines the opening. A plurality of adjusting units are disposed respectively and movably on the adjustment rods. Each of the adjusting units is movable on a respective one of the adjustment rods to vary the distance between a portion of the lid plate and a portion of the connecting member, which are, interconnected by the respective one of the adjustment rods, so as to adjust angle between the lid plate and the connecting member, thereby pressing the lid plate entirely against the wall of the housing. Because the lid plate can be adjusted so as to be parallel to the wall, there is no need for high precision during the manufacture and mounting thereof. Furthermore, the angle adjustment of the lid plate can maintain effectively the sealing of the vacuum chamber for a long amount of time.
In the preferred embodiment, a plurality of vertical partitions are fixed within a horizontal tubular member so as to divide the interior space of the tubular member into a plurality of consecutive vacuum chambers to thereby constitute a plurality of vacuum processing units. Each of the partitions has an opening sealed by a gate valve assembly, and is provided with a conduit therein, through which cooling water is forced to flow. As such, when the machining steps of the manufacturing process of a product are performed in sequence within the consecutive vacuum chambers, the product can move from one of the chambers to another through one of the openings. In this way, when all of the openings are unsealed, all of the chambers can be evacuated simultaneously to form a vacuum prior to machining the product, and it is only necessary to introduce air into the last one of the chambers for pressurization and unloading after the product has been machined.